Device for holding a ring-formed workpiece intended to be machined on its inner envelope surface

ABSTRACT

Device for holding a ring-formed workpiece with an inner and outer envelope surface and with transversal end surfaces which particularly are flat, which workpiece which for instance can consist of a ball race or any other conventional type of ring, when set up is to be subjected to machinging such as grinding or polishing and the like of the inner envelope surface, characterized by two holding members for holding the workpiece axially, each of which with one of its sides acts upon a transversal surface each and has one side provided with a circular surface, each of which surfaces are in contact with its opposite surface via a pressure-medium cushion or film for securing of the workpiece., one of the holding members then being capable of being driven, and by a number of transversal clamping jaws, which jaws are arranged at a distance from each other and can be put into contact with the outer envelope surface of the workpiece via a pressure-medium cushion or film whereby pressure medium cushions limit movements of the ring-formed workpiece axially in both directions as well as transversely in all directions.

United States Patent [191 J ohansson Feb. 5, 1974 1 DEVICE FOR HOLDING A RING-FORMED WORKPIECE INTENDED TO BE MACHINED ON ITS INNER ENVELOPE SURFACE [76] Inventor: Erik Lennart Waldemar .lohansson,

Gotabergsgatan 34, Goteborg, Sweden [22] Filed: June 15, 1971 [21] Appl. No.: 153,387

Primary ExaminerI-larold D. Whitehead Attorney, Agent, or Firm-Howson and l-lowson; Eugene E. Renz, Jr.

[ 5 7] ABSTRACT Device for holding a ring-formed workpiece with an inner and outer envelope surface and with transversal end surfaces which particularly are flat, which workpiece which for instance can consist of a ball race or any other conventional type of ring, when set up is to be subjected to machinging such as grinding or polishing and the like of the inner envelope surface, characterized by two holding members for holding the workpiece axially, each of which with one of its sides acts upon a transversal surface each and has one side provided with a circular surface, each of which surfaces are in contact with its opposite surface via a pressuremedium cushion or film for securing of the workpiece, one of the holding members then being capable of being driven, and by a number of transversal clamping jaws, which jaws are arranged at a distance from each other and can be put into contact with the outer envelope surface of the workpiece via a pressuremedium cushion or film whereby pressure medium cushions limit movements of the ring-formed workpiece axially in both directions as well as transversely in all directions.

4 Claims, 5 Drawing Figures Patented Feb. 5, 1974 3,789,553

4 Sheets-Sheet 1 Patented Feb. 5, 1974 4 Sheets-Sheet P- Patented Feb. 5, 1974 3,789,553

4 Sheets-Sheet I5 Patented Feb. 5, 1974 4 Sheets-Sheet L DEVICE FOR HOLDING A RING-FORMED WORKPIECE INTENDEDTO BE MACHINE!) ON ITS INNER ENVELOPE SURFACE The present invention relates to a device for holding a ring-formed workpiece with an inner and an outer envelope surface and with transversal end surfaces. An example of such a workpiece is a ball race. The holding device is to have such properties that it can hold the ball race, or any other conventional type of ring, although a ball race has been chosen as an example of an embodiment in this specification, but which in the following will simply be referred to as a ring, in such a way that its inner envelope surface can be machined, for instance through grinding or polishing, while maintaining stringent requirements stipulated for the envelope surface. At such machining of rings, the ring itself, during the course of the machining, has been subjected to certain reciprocal transversal movements, which are undesirable, as the requirements stipulated then cannot be completely fulfilled.

The purpose of the present invention is to achieve a substantial damping of the above-mentioned transversal movements, and this is achieved according to the present invention in that the ring, both transversally and axially, is set up in such a way that pressuremedium cushions r films limit the movements of the ring axially, and then in both directions, as well as transversally, also in all directions.

According to an appropriate embodiment, the ring is held transversally by one or a plurality of clamping jaws, for instance three clamping jaws, so that the ring will have three-point suspension. Between each clamping jaw and the outer envelope surface of the ring a pressure medium is applied, so that a pressure-medium cushion or film arises.

Further, according to another suitable embodiment the ring is held at both of its side surfaces by a holding member on each side, of a disc-formed character, the outer surfaces which are not in contact with the ring then being opposite a surface each via a pressure medium, and the last-mentioned surfaces can then move towards each other under the influence of the pressure, so that the ring is clamped axially between two pressure-medium cushions.

In view of the above-mentioned arrangement, the ring is thus clamped both transversally and axially between pressure-medium cushions, which have the capa- I bility of damping undesirable movements that are applied to the ring.

The characteristic properties of the present invention are specified in more detail in the claims.

The present invention will be described in more detail in conjunction with the attached drawings, in which FIG. 1 shows the device for holding a ring which is to be machined internally, and the device is then shown in the position where it is about to receive a ring,

FIG. 2 shows the ring secured transversally, and the axial clamping has commenced,

FIG. 3 shows the ring entirely secured both transversally and axially,

FIG. 4 shows a cross-section of the device according to FIG. 3 just before the axial clamping has been completed and before pressure medium is fed to the device, in which FIG. 5 shows the device with the ring entirely clamped and with pressure medium applied.

In the FIG., 1 is a ring with a square cross-section. In this ring there is a ring 3 arranged, which has a square cross-section.

On its peripheral surface the ring is provided with a radial peripheral flange 4, which runs in a groove 5, made in the wall 6. The groove5 has two opposite groove walls, the distance between which exceeds the thickness of the radial flange 4. This involves that the ring 3 can move axially between the walls 7, and between the wall 7 and the flange 4 a spring arrangement or the like 8 can appropriately be arranged. The bottom of the peripheral groove 5 is connected with a drilled hole 5A for the supply of pressure medium. The ring 3 has a flat right side surface 9 in which a flat contact surface is milled, where two parts have been given the reference designations 10 and 11. In the contact surface 9, two peripheral channels or pockets 12 and-13 have been made for pressure medium. These channels 12 and 13 are connected to pressure medium conductors or drilled holes 14, one of which can be seen in FIG. 1. The ring-formed holding member 15 is in contact with the contact surface containing the parts 10 and 11. At its inner edge, said member is provided with a tubular, cylindrical hub 17, the outer surface of which is intended to be in contact with'a workpiece. The ring-formed member has an outer peripheral surface 18, which is opposite an inner peripheral surface 19 of aring 20. The purpose of the ring 20 is to limit the axial and transversal movements of the holding member 15. On its left side, the holding member is connected with a bow 21 made of spring steel or the like, which is connected in its center to a shaft 22. Through the bow 21 and shaft the holding member 15 can be caused to rotate around its axis.

To the right of the ring 1 a guidingjaw 23 is arranged, which has two ring-formed square contact surfaces 24 and 25. These contact surfaces each enclose pockets 26 and 27 for the supply of pressure medium through the drilled holes 28 and 29. The two contact surfaces 24 and are made in such a way that their overall surfaces constitute two supporting points for the outer envelope surface of a cylindrical ring.

To the left of the ring 1, a clamping jaw 30 is moreover arranged, which contains a ring-formed contact surface 31 which encloses a cavity 32 for pressure medium, which is supplied via a drilled hole 33. This clamping jaw is rotatable around an axle 34. Together with the contact surfaces 24 and 25, the contact surface 31 achieves three-point suspension or, more precisely, three-surface suspension, of a cylindrical ring.

On the right side of the clamping jaws 23 and 30, a disc-formed flange 35 is shown, which has a flat left side 36. In the side surface 36, a contact surface with two parts 37 and 38 has been milled. Between said two parts, channels 39 and 40 have been made, which are intended for pressure medium, and the channel 40 is then divided into pockets. The channels are connected to a number of drilled holes, for the supply of a pressure medium. In contact with the parts 37 and 38 there is a contact surface 43 on the ring-formed holding member 42. The holding member has an oblique peripheral surface 44, which is opposite an oblique inner peripheral surface 45 of a ring 46. The purpose of the ring is to limit the axial and transversal movements of the holding member 42. At its inner edge, the holding member 42 is provided with a tubular, cylindrical hub 47, the end surface of which is intended to coact with the side surface of a ring 48. The ring has an outer envelope surface 49 and an inner envelope surface which are to be machined.

There is shown in the drawings an axle 50 provided with a grinding wheel 51. I

The device described above for holding a cylindrical ring for machining of its inner envelope surface functions in the following way.

From FIG. 1 it will be noted that the two holding members and 42 are located at such a distance from each other, and the clamping jaws 23 and 30 are located in such a way that the ring 48 can be inserted and placed in contact with the surfaces 24 and 25, after which the surface 31 can also be put into contact. The ring is then secured transversally. It should be obvious that, although only three clamping surfaces are shown,

surfaces of the ring 48. it is then advisable to use a 7 member not shown to move the ring 35 towards the ring 1. When this has been done, there is also the possibility of making a fine adjustment, by clamping the ring by feeding pressure medium to the drilled hole 5A so that the ring 3 will be moved towards the right. It should be obvious that in many cases it is sufficient to have the rings 1 and 35 more or less stationary continuously, while the ring 3 is moved axially when changing the ring 48, at the same time as the clamping jaws 23 and 29 are moved away from each other. When the ring 48 is very close to the definite clamping, as will be noted from FIG. 3, and still better from FIG. 4, a certain further clamping movement is required, both axially and transversally. This clamping is not completed until pressure medium has been supplied to the channels l2 and 13, the cavities 27, 26 and 32, and the channels 39 and 40. When this has been done, the further clamping takes place.

From FIG. 5 it will be noted that the outer envelope surface of the ring 48 is in contact with the clamping jaws 23 and via pressure medium cushions or films. Thus, the envelope surface49 has no metallic contact. The sides of the ring 48 are in contact with the hubs 17 and 47 of the holding members 15 and 42. The holding members, in turn, have their side surfaces 16 and 43 in direct contact with pressure-medium cushions or pressure-medium films. Further, through their oblique peripheral surfaces 18 and 44, the holding members are also in contact with pressure-medium cushions or films. Thus, the ring 48 is also via the holding members 15 and 42 in contact with pressure-medium cushions of films, both transversally and axially.

Due to the presence of the above-mentioned pressure-medium cushions or films, the ring 4 can withstand undesirable stresses in any direction whatsoever, without any detrimental influence on the machining, since said pressure-medium cushions or films dampen such undesirable movements, 7

in the foregoing it has not been mentioned what kind of pressure medium can be used, but it should be obvious that any conventional pressure medium whatsoever can be used, such as coolant, water, or compressed air.

It should be obvious that all or some of the pressuremedium conductors can be provided with valve controls, so that automatic setting of an inserted ring is possible. It is then advisable to have said peripheral channels divided up so that a number of pockets will be formed which have a separate supply of pressure medium. lf fluid is used as a pressure medium, the laws of hydrostatic suspension and thereby self-centering will then of course be applicable.

' lf fluid is used in the device described, the suspension will act hydrostatically. However it should be obvious that the suspension can be converted in a known way to hydrodynamic suspension. Under certain circumstances, the slots 18, 19 and 45 can have such a width that pressure-medium cushions or films will not be formed.

lclaim:

1. Device for supporting a ring-formed workpiece with an inner and outer envelope surface and with transversal axial end surfaces comprising a pair of bolding members adapted to engage the axial end surfaces of said workpiece to support the workpiece axially, each of said holding members including a ring member engageable with the axial end surface and mounted for floating movement in the holding member by fluid pressure means, means for rotating one of said holding members and a plurality of clamping jaw members each having an enclosed pocket confronting the outer envelope surface of said workpiece, fluid pressure means for pressurizing said pockets to provide a fluid cushion support whereby pressure medium cushions limit movements of the ring-formed workpiece axially in both directions as well as transversly in all directions.

2. Device according to claim 1, characterized in that each holding member consists of a ring-formed disc.

3. Device according to claim 1, characterized in that each disc, at its inner edge, is provided with a tubular hub, the outer end of which is intended to be in contact with the end surfaces of the workpiece.

4. Device according to claim 1, characterized in that either of the rings that are to be capable of being driven have torque imparted to them via one or a plurality of plate springs. 

1. Device for supporting a ring-formed workpiece with an inner and outer envelope surface and with transversal axial end surfaces comprising a pair of holding members adapted to engage the axial end surfaces of said workpiece to support the workpiece axially, each of said holding members including a ring member engageable with the axial end surface and mounted for floating movement in the holding member by fluid pressure means, means for rotating one of said holding members and a plurality of clamping jaw members each having an enclosed pocket confronting the outer envelope surface of said workpiece, fluid pressure means for pressurizing said pockets to provide a fluid cushion support whereby pressure medium cushions limit movements of the ringformed workpiece axially in both directions as well as transversly in all directions.
 2. Device according to claim 1, characterized in that each holding member consists of a ring-formed disc.
 3. Device according to claim 1, characterized in that each disc, at its inner edge, is provided with a tubular hub, the outer end of which is intended to be in contact with the end surfaces of the workpiece.
 4. Device according to claim 1, characterized in that either of the rings that are to be capable of being driven have torque imparted to them via one or a plurality of plate springs. 